The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to the incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
The materials used in waveguides and resonators have long influenced the type of mode families and the strength of mode families produced by a laser beam. Selecting one or more mode families typically depends on altering a geometry of the materials used. EP2362502 to Rofin, for example, discloses a mode selection technique that allows a mode to be selected by introducing a pit in a surface of a waveguide in the laser. The length of the pit helps to select the lowest order mode when needed. Cutting such a pit, however, requires great precision in the dexterity of the tools involved.
U.S. Pat. No. 5,745,511 to Leger allows a user to select a mode family by first calculating the required mirror reflectance that is needed for that mode family, and then by producing a mirror that has the needed mirror reflectance. Leger's mirror, however, may produce other mode families that are not wanted, and are only accurate to within 50 μm in size. Because Leger depends upon a chemical etching process to produce such mode-selecting mirrors, smaller mirrors for powerful lasers could not be made.
US20030147445 to Zeitner teaches a waveguide resonator that has a waveguide that is thinned near the facets of the waveguide in order to produce phase structures that increase circulating losses for specified modes. Zeitner's method, however, only allows the areas of the waveguide near the facets to be modified, which limits the types of modes that can be eliminated. Zeitner's method also can only be applied to resonators made of a plurality of materials, which tend to have a lower Q factor than monolithic resonators.
US20090154503 to Peyghambarian teaches a method of selecting a mode by using a chemical dopant that absorbs light at some wavelengths, but allows light to pass through at other wavelengths. Preselected mode families will use resonators and waveguides made from dopants that allow only wavelengths capable of producing light within the preselected mode families. There are some mode families, however, that do not have a corresponding dopant that is selective enough to allow only the desired wavelength to pass through the resonator. Under such circumstances, older techniques must be used.
Thus, there remains a need for improved systems and methods for selecting mode families in monolithic resonators.